Navigational aids are tools used to help people navigate in the air, on land, and at sea. LORAN is an acronym for Long Range Navigation, a system of radio signals used to determine a ship or aircraft's position. SONAR stands for Sound Navigation and Ranging, a technique used to detect objects underwater. RADAR is an acronym for Radio Detection and Ranging, a system that uses radio waves to detect objects and measure their distance. MAP stands for MAP, a two-dimensional representation of a geographical area. LODESTAR is a star used as a navigational aid. CHART is a MAP used to show the depths of water and other features of a body of water. CANAL is a man-made waterway used for transportation. STARMAP is a MAP of the stars in the night sky.